Characteristics and Health Care Utilization of Patients With Housing Insecurity in the ED

Key Points Question What is the scope of housing insecurity for patients presenting to a major emergency department in the Southeast US? Findings In this cross-sectional study of 23 795 emergency department visits, in 5% of visits, patients screened positive for housing insecurity. Patients experiencing homelessness were more likely to present with a chief concern of suicide, to be uninsured, and to have multiple visits during the study period. Meaning This study supports screening for homelessness in emergency departments, directing resources toward mental health care, and focusing on high utilization as vital steps in optimizing care for patients with housing insecurity.


Introduction
More than 653 000 people experienced homelessness in the US on a single night in 2023, 1 and more than 1.2 million people in the US spent at least 1 night in an emergency shelter or transitional housing program in 2021. 2 Homelessness in Tennessee increased by 45.6% from 2020 to 2022, the third largest increase among states. 1On a single night in January 2023, 2129 people were identified as homeless in Nashville via a point-in-time estimate. 3Given the difficulty of counting this population, these numbers likely underestimate the true population of individuals experiencing homelessness. 4stable housing and homelessness can exacerbate adverse and inequitable health outcomes.Individuals experiencing homelessness are at greater risk of chronic diseases, infectious diseases, injury, and disability, [5][6][7][8] leading to increased acute hospital visits and emergency department (ED) morbidity and mortality. 9,10Even as recognition of housing as a social determinant of health expands, [11][12][13][14] housing status is infrequently addressed when creating care plans. 15Reliable, accurate, and timely identification of those at risk of or currently experiencing homelessness is vital for effective interventions and safe discharge.
Paradoxically, there is no universal method in health care settings to identify patients experiencing homelessness despite regulatory movement to increase hospital-level screening for social determinants of health. 16In 2012, the Veterans Health Administration began to use the Homelessness Screening Clinical Reminder (HSCR), a 2-question screening tool, within its outpatient clinics.These questions asked: 1.In the past 2 months, have you been living in stable housing that you own, rent, or stay in as part of a household?(Negative response indicates current unhoused status.) 2. Are you worried or concerned that in the next 2 months you may not have stable housing that you own, rent, or stay in as part of a household?(Positive response indicates risk of future homelessness.)This screening was implemented and validated in the Veterans Health Administration system, where question 2 predicted future shelter entry. 17Following the HSCR implementation, clinicians reported that this information influenced clinical decision-making and care plans. 18In 2023, the Centers for Medicare & Medicaid Services introduced mandatory screening for social determinants of health, including housing instability, for admitted patients but not for EDs. 16though screening tools are being implemented, 19,20 to our knowledge, few studies have described patients at risk of or currently experiencing homelessness who present to an urban ED using a systematic screening method.Even fewer have assessed prevalence of homelessness among individuals presenting to acute care centers.[23] This study quantified the prevalence of homelessness and housing insecurity among all patients who sought care in an urban ED in the Southeast US using the HSCR.We describe the demographics, method of arrival, diagnoses, acuity, timing of presentation, disposition, and insurance status for ED patients experiencing homelessness.In addition, given that about one-fourth of people experiencing homelessness in Nashville are unsheltered, 3 we examined whether weather was associated with ED visits.Finally, because patients experiencing homelessness use EDs more frequently than others, 15,24,25 we examined repeat visits.These data may provide a baseline to guide future hypothesis-driven interventions.

Methods
This cross-sectional study was performed at the Vanderbilt University Medical Center (VUMC), an academic tertiary care center in Nashville, Tennessee.The HSCR screening was administered by registration staff during ED visits.All patients who answered "no" to question 1 were coded as homeless.Remaining patients who answered "yes" to question 2 were coded as unstably housed.Either designation led to an automatic notification of the ED social work team.For analysis, we grouped those who screened positive for current homelessness and risk of future homelessness into 1 category coded as insecure housing (Table 1).
In this descriptive, cross-sectional study, data were collected on VUMC ED adult patients (aged Ն18 years) for visits from January 5, 2023, when the screening was implemented, to May 16, 2023, when procedures changed (from registration staff screening to patient self-report).Additionally, we collected data directly from the electronic medical record (EMR) on patient age, race (self-reported using EMR-coded categories during patient registration), ethnicity (self-reported), gender (self-reported), preferred language, insurance status, ED visit date, arrival time and method, presenting symptom, primary discharge diagnosis, disposition plan, and whether a member of the social work team was able to see each patient who screened positive on either question.Race categories included American Indian or Alaska Native; Asian; Black or African American; Hispanic, Latino, or Latina (we relied on categories in the EMR for the race categories, and some people identified their race as Hispanic or Latino while others may have defined their race as White and their ethnicity as Hispanic or Latino; there are different numbers as some patients left fields blank while others did not); Middle Eastern or North African; White; multiracial; other (those with response of "none of these," "unable to provide," and "prefer not to answer"); and unknown.Ethnicity categories were Hispanic, Latino, or Latina; not Hispanic, Latino, or Latina; other (those with response of "none of these," "unable to provide," and "prefer not to answer"); and unknown.Race and ethnicity were included given that historical marginalization of racial and ethnic minority populations puts these individuals at greater risk.We recognize that race and ethnicity are social constructs; however, structural racism is linked to medical outcomes in the US.This phenomenon is particularly salient for individuals experiencing homelessness.In our article, we are not implying biologic significance, but include race to bring attention to racial and ethnic disparities present in this patient population.
Gender categories included female, male, and unknown.The Emergency Severity Index (ESI) triage score, a standardized method of assessing acuity that ranges from ESI level 1 (most critically ill) to level 5 (least critically ill), 28 was collected at admission.We categorized individual chief concerns and primary ED diagnoses for each visit.Finally, we downloaded Nashville International Airport weather station data from the National Oceanic and Atmospheric Administration. 29

Statistical Analysis
We first present descriptive statistics, stratified by housing status (secure housing, insecure housing, and missing) for patient characteristics by visit.We then assessed how many unique patients visited the VUMC ED during the study period and how many of the encounters were for patients with 1, 2, 3, 4, or 5 or more visits.We repeated the descriptive analysis for patients who presented more than 3 times during the 4.5-month study period (defined as high utilization).We then aggregated housing screening data within each month, day of the week, and time of day to describe the prevalence and timing of visits.We generated prevalence 95% CIs from 1000 bootstrapped samples.We used locally estimated scatterplot smoothing to assess the association between daily prevalence by daily minimum, maximum, and average temperature and precipitation.
Data were analyzed in R, version 4.2.2 (R Project for Statistical Computing). 30The R code is available for review online. 31

Results
From January 4 to May  2). 32,33They were also more likely among visits by male patients (829  2). 32,33Visits with a missing housing screening were also more likely to end with the patient leaving without being seen (378 Of all 660 individual patients who screened positive for housing insecurity, 80 (11%) had 3 or more visits during the study period (high utilization) compared with 725 of 18 372 patients (4%) who screened negative (Figure 1A).Patients with high utilization accounted for 39% (469) of all visits with positive screening results compared with 13% (3027) of visits with negative screening results (Figure 1B).Among patients with a positive screening result, those with high utilization were more  a Indicates fewer than 5 visits characterized within a cell to avoid inadvertently identifying participants. 32Included "none of these," "unable to provide," and "prefer not to answer." c The triage score is presented as the Emergency Severity Index, with level 1 indicating most critically ill and level 5 indicating least ill. 33All data are presented at the level of the visit.
likely than those with a negative screening result to have pending (19 [4%]  Although the data showed a relatively stable percentage of homelessness by month (Figure 2A)   and day of the week (Figure 2B), a higher percentage of visits with positive screening results occurred from 8 PM to 6 AM than from 6 AM to 8 PM (Figure 2C).This finding could be due to the lower number of visits with negative screening results overall during those hours (eFigure 3 in Supplement 1).There was no meaningful association between the percentage of visits with a positive screening results and rainfall, minimum temperature, or maximum temperature (eFigure 4 in Supplement 1).Finally, the social work team was able to conduct evaluations at 919 of the 1185 visits (78%) among patients who screened positive for homelessness and/or housing insecurity.

Discussion
To our knowledge, no universal method exists within EDs to identify patients experiencing housing insecurity and to systematically provide support for their needs.Screening for housing insecurity is uncommon among standard ED protocols, and housing status is rarely recorded in patient medical records. 19,34We believe that identifying housing instability, which often co-occurs with other structural inequalities, 35 is the first step in delivering health care that truly addresses social determinants of health.
Although prior studies have found that patients experiencing homelessness are more likely to visit the ED than are patients who are housed, 15,25 few have used data gathered from the EMR to understand this patient population. 6Through implementation of the 2-question HSCR within the ED at an urban Southeast US hospital, we found demographic and health care utilization differences between housed individuals and those experiencing housing insecurity.

Homelessness and Housing Insecurity
Although the literature estimating the proportion of homelessness in health care settings is variable, our findings (5% positive) fall in the middle of the wide range of previously published rates. 22Most prior estimates of homelessness and housing insecurity were from oral surveys or indirect quantifications, such as "homeless" listed as the patient address or chief concern.Databases on randomly assigned 1-week reporting periods in which physicians collected patient data generated a lower estimate of 0.7% of all visits across the US. 22,36This discrepancy may stem from inconsistent physician querying of housing status or other sources of reporting bias.Conversely, 3 studies relying on randomly selecting individuals to interview in urban EDs found a higher proportion of people experiencing homelessness at 14% to 35%. 4,21,23This finding may indicate regional differences, variations between academic and community hospitals, or unconscious bias in who was approached to complete surveys.Conversely, our study relied on standardized questions during patient registration.In line with our findings, a large prospective study using components of the HSCR to screen consenting adults in 3 Pennsylvania EDs found that 7% were experiencing homelessness. 37reening all ED patients using a protocolized, systematic strategy likely offers a more reliable quantification of patients experiencing homelessness than relying on diagnostic codes or inconsistent patient querying, a hypothesis that remains a key area of future work.

Patient Characteristics
The higher proportion of male, middle-aged, and Black patients among those who screened positive is in line with previous studies and point-in-time counts in Nashville. 3,38As in previous studies, 38,39 patients with positive screening results were also more likely to arrive by ambulance or public transportation.Transportation barriers faced by people experiencing homelessness may contribute to delayed access to care. 40,41Furthermore, use of ambulance transportation for nonemergency conditions makes emergency medical services vehicles and crews unavailable for patients who require urgent transport and may lead to increased health care costs and burnout among emergency medical services providers. 42nally, as in the existing literature, 23

Chief Concerns and Diagnoses
4][45][46] In line with other studies, [47][48][49] ED visits for patients with housing insecurity or homelessness were more likely to include a chief concern and primary diagnosis related to suicide, intoxication, or trauma.Discharge was more likely to be to psychiatric care for those who screened positive than for those who screened negative.Finally, there was concordance between presenting chief concern and primary diagnosis, suggesting that homeless individuals are not at increased odds of malingering or fabricating symptoms to get food or shelter, as has been suggested by some prior studies. 46,50The proportion of visits with positive screening results at night suggests the continued need for support and homeless preparedness in EDs overnight.
Overall, these findings point to a need for more comprehensive psychiatric care, including suicide prevention and support for treating substance use disorders for patients experiencing homelessness as well as additional community support and bolstered coordination between EDs and mental health care facilities.Finally, continued efforts should be made to maintain resources overnight and bring mental health care directly to the street. 46

High Utilization
It is well established that patients experiencing homelessness access the ED more than patients who are housed and that patients categorized as having high utilization account for a sizable proportion of these visits. 15,24That was true in our study, in which people screening positive for homelessness were more likely to log 3 or more ED visits during the study period and represented a disproportionate proportion of visits.
This finding supports data suggesting that those experiencing homelessness are more likely to use the ED with greater frequency but, most importantly, points to a small proportion of individuals experiencing homelessness constituting a considerable proportion of visits.If additional resources can be directed to this relatively small group of individuals, the impact could be significant.That patients with high utilization were more likely to present with a primary diagnosis related to suicide and to be insured with Medicaid further supports the need for improved mental health care and coordination with psychiatric hospitals and insurers.
Future studies should aim to include more institutions and regions.One evaluation of 2 screening tools across 11 sites found that some patients screened positive for homelessness with one tool but not the other and advised caution when selecting a screening tool, as homelessness does not have a single, universal definition. 51Accordingly, in addition to providing a more accurate picture of homelessness and housing insecurity in the region, we hope this study may serve as a call for the implementation of standardized screening for homelessness across all EDs.Understanding details of the previously underrecognized population experiencing homelessness will enable our center to continue directing resources to improve health and social conditions that lead to health inequities.
Specifically, we are using these data to develop a multidisciplinary homeless health care team that includes in-hospital and street medical care for people experiencing homelessness and housing insecurity.Findings from this study point to the importance of homeless health and street medicine initiatives within hospitals, especially to target patients who use the ED regularly.They highlight the need for robust coordination between EDs and psychiatric hospitals and continued advocacy for targeted resources for these patients.Through systematic screening and connection to social work, we hope to advance health equity, reduce health care costs, and improve health outcomes for patients experiencing homelessness.

Strengths and Limitations
Our study has strengths, including the implementation of our screening process (leading to 90% completion).Through interviews, we found that registration staff felt that the screening fit easily into their workflow, social workers were motivated because they were helping more patients experiencing homelessness, and while many physicians did not seem aware of the screening, they did alter their care for patients who they identified as experiencing homelessness.
This study has several limitations.First, housing screenings were marked as "unable to obtain" at 10% of visits, likely due to these patients arriving with immediate, life-threatening illness or trauma or leaving without formal discharge.An ongoing quality improvement project aims to better understand patients with missing screenings.Second, as a highly specialized referral center, 26 VUMC is frequently full (diverting ambulances to other local or regional hospitals), which may underestimate the prevalence of ED visits by people experiencing homelessness in the region.Third, data such as primary diagnosis and chief concern of the patient were obtained retrospectively from the EMR and are therefore prone to misclassification.Notably, as a descriptive study, we are not able to imply causation but rather associations between primary diagnosis, chief concern, demographic information, or weather and housing status.

Conclusions
In this cross-sectional study, through implementation of a universal screening process in the ED using registration and the EMR, we identified and described the population with housing insecurity presenting to the ED.Of 23 795 ED visits, at 5%, patients screened positive for housing insecurity and were more likely to present with a chief concern of suicide, to be uninsured, and to have multiple visits during the study period.

Figure 1 . 1 A
Figure 1.Utilization of the Vanderbilt University Medical Center (VUMC) Emergency Department (ED) Between January 5 and May 16, 2023

Figure 2 .
Figure 2. Visits With Patients Screening Positive for Housing Insecurity Between January 5 and May 16, 2023

Table 1 .
Coding of Responses to Homelessness Screening Clinical Reminder 16, 2023, a total of 23 795 VUMC ED housing screenings were completed for adult patients as a part of standardized patient registration (12 465 visits among females [52%], 11 329 [48%] among males, and 1 [<1%] among those with unknown gender]; median age, 47 years [IQR, 32-48 years]).Of the total visits, less than 1% were among American Indian or Alaska Native patients; 2% among Asian patients; 22% among Black or African American patients; 5% among Hispanic, Latino, or Latina patients; less than 1% among Middle Eastern or North African patients; 68% among White patients; 1% among multiracial patients; and less than 1% among patients with other race.By ethnicity, 8% of visits were among Hispanic, Latino, or Latina patients; 91% among non-Hispanic, non-Latino, or non-Latina patients; and less than 1% among those with other ethnicity.Of 1185 visits with positive screening results (5% [660 unique patients]), at 1065, patients screened positive for homelessness, and at 120, patients screened positive for unstable housing.An additional 2776 visits (10%) were missing a screening secondary to severe trauma, patients leaving without being seen, or discharge prior to screening completion.Of visits with positive screening results, the median age of patients was 46 years (IQR, 36-55 years); 356 (30%) were among female patients and 829 (70%) among male patients.At 22 610 visits (95%), the screening result was negative.Positive screening results were more likely among visits for people aged 35 to 64 years (853 [72%]) compared with screening negative for homelessness and/or housing instability (10 400 [46%]) and less likely among those aged 75 years or older (6 [0.5%] vs 2436 [11%]) (Table

Table 2 .
Characteristics of Patients With Visits to the ED at Vanderbilt University Medical Center Between January 5 and May 16, 2023, by Housing Status

Table 2 .
Characteristics of Patients With Visits to the ED at Vanderbilt University Medical Center Between January 5 and May 16, 2023, by Housing Status (continued)

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positive screening results were more likely among uninsured patients or those enrolled in Medicaid.This finding may point to the continued need for